The present invention relates to an embroidery data processing system for calculating stitching points for an embroidery design to be made by an automatic sewing machine.
Formation of an embroidery design on a foundation fabric with an automatic sewing machine requires information about stitch positions which indicate stitching points of the embroidery design. U.S. Pat. No. 4,388,883, for example, discloses a system for processing such stitch position information to be supplied to an automatic sewing machine. According to the disclosed processing system, an embroidery design to be formed on a fabric is represented by a combination of polygonal blocks. Stitching points of the embroidery design are calculated from such simple items of information given to the system as the positional coordinates of the vertexes of each block and the thread density of stitches to be formed in each block.
When an embroidery design is formed based on such calculated stitching points, it has clear boundary lines B 1 between adjacent blocks as shown in FIG. 19 of the accompanying drawings. However, such clear boundary lines may not be desirable in some embroidery works. For example, it is preferable for an embroidery design of a scenery not to have clear boundary lines but to have blurred or indistinct boundary lines as shown in FIG. 20. The known processing system is however unable to form such an embroidery design.
In order to make an embroidery work with indistinct boundary lines, it has heretofore been necessary to prepare information as to all stitching points, which is a very laborious and time-consuming process. Particularly, stitching points are positioned in a complex pattern across a boundary line B between adjacent blocks, and it has been highly difficult to determine each of such stitching points in advance.
If stitching points are to be differently positioned across a boundary line, i.e., if a boundary line is to be blurred differently, then information about all stitching points has to renewed. Therefore, design changes cannot quickly be carried out.
Another known processing system disclosed in U.S. Pat. No. 4,520,745 processes stitching point information about a sectorial block. According to this system, every other stitching point on a radially inner side of a sectorial block is positionally shifted into the block, thus preventing stitches from being too crowded on the radially inner side.
In the conventional embroidery processing systems, stitching points are formed in principle on opposite sides staggered across a side or boundary line, the embroidery design must be divided into as many blocks as the number of such staggered stitching point. For example, when an embroidery design having a staggering righthand side is to be formed as shown in FIG. 21, it is necessary to divide the embroidery design into a great number of blocks U1V1V2U2, U2W1W2U3, U3V3V4U4, . . . associated with respective staggering stitching points as shown at an enlarged scale in FIG. 22.
Consequently, when such an embroider work with staggering stitching points across a side is to be formed, as many items of information about stitching points must be prepared as the number of all stitching points. The preparation of those items of information requires a large expenditure of labor and time.
If an embroidery design is to be differently blurred or staggered across one or both sides, i.e., if stitching points are to be positioned in a different staggering pattern across one or both sides, then the embroidery design has to be newly divided. Therefore, no quick changes in embroidery designs have been possible.